This project is designed to maintain and expand already established breeding colonies of two strains of cats afflicted with counterparts of the Maroteaux-Lamy Syndrome and Hurler of Hurler-Scheie Syndrome in man, and to further characterize the modes of inheritance and pathogenetic mechanisms in these disorders. The findings will be used as a basis for assessing therapeutic experiments in the cat. Methodology involves light and electron microscopy, analysis of glycosaminoglycan types and concentrations, and enzyme activity in various tissues. Fibroblast cultures will be used for cross-correction experiments. Purified enzyme and allotransplantation will form the basis of the therapeutic experiments which will be evaluated by monitoring the progression of pathological changes of these disorders in treated and untreated cats.